1 files changed, 38 insertions, 0 deletions
diff --git a/pkg/cpuid/cpuid.go b/pkg/cpuid/cpuid.go
new file mode 100644
index 000000000..f7f9dbf86
--- /dev/null
+++ b/pkg/cpuid/cpuid.go
@@ -0,0 +1,38 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package cpuid provides basic functionality for creating and adjusting CPU
+// feature sets.
+//
+// To use FeatureSets, one should start with an existing FeatureSet (either a
+// known platform, or HostFeatureSet()) and then add, remove, and test for
+// features as desired.
+//
+// For example: on x86, test for hardware extended state saving, and if
+// we don't have it, don't expose AVX, which cannot be saved with fxsave.
+//
+//   if !HostFeatureSet().HasFeature(X86FeatureXSAVE) {
+//     exposedFeatures.Remove(X86FeatureAVX)
+//   }
+package cpuid
+
+// Feature is a unique identifier for a particular cpu feature. We just use an
+// int as a feature number on x86 and arm64.
+//
+// On x86, features are numbered according to "blocks". Each block is 32 bits, and
+// feature bits from the same source (cpuid leaf/level) are in the same block.
+//
+// On arm64, features are numbered according to the ELF HWCAP definition.
+// arch/arm64/include/uapi/asm/hwcap.h
+type Feature int